Inhibitors of human immunodeficiency virus (HIV) protease have been approved for use in the treatment of HIV infection for several years. A particularly effective HIV protease inhibitor is (2S,3S,5S)-5-(N—(N—((N-methyl-N-((2-isopropyl-4-thiazolyl)methyl)amino)carbonyl)-L-valinyl)amino)-2-(N-((5-thiazolyl)-methoxycarbonyl)amino)-1,6-diphenyl-3-hydroxyhexane (ritonavir), which is marketed as NORVIR®. Ritonavir is known to have utility for the inhibition of HIV protease, the inhibition of HIV infection, the inhibition of cytochrome P450 monooxygenase and the enhancement of the pharmacokinetics of compounds which are metabolized by cytochrome P450 monooxygenase. Ritonavir is particularly effective for the inhibition of HIV infection when used alone or in combination with one or more reverse transcriptase inhibitors and/or one or more other HIV protease inhibitors.
Ritonavir and processes for its preparation are disclosed in U.S. Pat. No. 5,541,206, issued Jul. 30, 1996. This patent discloses processes for preparing ritonavir which produce a crystalline polymorph of ritonavir which is termed crystalline Form I. Substantially pure Form I has the powder X-ray diffraction pattern, 13C solid state nuclear magnetic resonance spectrum, the FT near infrared spectrum and the FT mid infrared spectrum which appear in FIGS. 1, 4, 6 and 8, respectively. The angular positions (two theta) of the characteristic peaks in the powder X-ray diffraction pattern of substantially pure Form I shown in FIG. 1 are 3.33°±0.1°, 6.76°±0.1°, 8.33°±0.1°, 14.61°±0.1°, 16.33°±0.1°, 16.76°±0.1°, 17.03°±0.1°, 18.02°±0.1°, 18.62°±0.1°, 19.47°±0.1°, 19.86°±0.1°, 20.25°±0.1°, 21.46°±0.1°, 23.46°±0.1° and 24.36°±0.1°.
Another process for the preparation of ritonavir is disclosed in U.S. Pat. No. 5,567,823, issued Oct. 22, 1996. The process disclosed in this patent also produces ritonavir as crystalline Form I.
Pharmaceutical compositions comprising ritonavir or a pharmaceutically acceptable salt thereof are disclosed in U.S. Pat. Nos. 5,541,206, issued Jul. 30, 1996; 5,484,801, issued Jan. 16, 1996; 5,725,878, issued Mar. 10, 1998; and 5,559,158, issued Sep. 24, 1996 and in International Application No. WO98/22106, published May 28, 1998 (corresponding to U.S. Ser. No. 08/966,495, filed Nov. 7, 1997).
The use of ritonavir to inhibit an HIV infection is disclosed in U.S. Pat. No. 5,541,206, issued Jul. 30, 1996. The use of ritonavir in combination with one or more reverse transcriptase inhibitors to inhibit an HIV infection is disclosed in U.S. Pat. No. 5,635,523, issued Jun. 3, 1997. The use of ritonavir in combination with one or more HIV protease inhibitors to inhibit an HIV infection is disclosed in U.S. Pat. No. 5,674,882, issued Oct. 7, 1997. The use of ritonavir to inhibit cytochrome P450 monooxygenase and to enhance the pharmacokinetics of compounds metabolized by cytochrome P450 monooxygenase is disclosed in WO97/01349, published Jan. 16, 1997 (corresponding to U.S. Ser. No. 08/687,774, filed Jun. 26, 1996).
It has now been unexpectedly discovered that ritonavir can be prepared as a new crystalline polymorph which is termed crystalline Form II.
All publications, issued patents and patent applications cited herein are hereby incorporated by reference.